PAGES2017: New Cherry Pie

Rosanne D’Arrigo once explained to an astounded National Academy of Sciences panel that you had to pick cherries if you wanted to make cherry pie – a practice followed by D’Arrigo and Jacoby who, for their reconstructions, selected tree ring chronologies which went the “right” way and discarded those that went the wrong way – a technique which will result in hockey sticks even from random red noise. Her statement caused a flurry of excitement among Climategate correspondents, but unfortunately the NAS panel didn’t address or explain the defects in this technique to the lignumphilous paleoclimate community.

My long-standing recommendation to the paleoclimate community has been to define a class of proxy using ex ante criteria e.g. treeline black spruce chronologies, Antarctic ice cores etc., but once the ex ante criterion is selected, use a “simple” method on all members of the class. The benefits of such a procedure seem…